Protozoa Animal like Protists

Evolutionary Perspective Protozoan is a complete organism in which all life activities are carried on within a single membrane First fossil evidence of cells containing membrane bound structures 1.5 billion years old Archaea and Eubacteria contributed to the origin of protists Endosymbiont hypothesis explains how this could have occurred Six phylogenitic protist Super groups are recognized All protist groups were present by the cambrian period

Life within a single cell Maintaining Homeostasis with organelles Pellicle- microtubules under the cell membrane, maintains shape but is flexible Cytoplasm differentiated into two regions Ectoplasm- clear and firm Endoplasm- granular more fluid Contractile Vacuoles- expel excess water Nutrition Cytopharnyx- ingests larger food (mouth) Endocytosis- thru membrane forms food vacuole Smaller nutrients enter by active transport across membrane Egestion vacuole expels undigested wastes

Single Cell Protozoa are so small they have high surface area to volume ratio which facilitates difusion Gas exchange of oxygen and carbon dioxide occurs easily Excretion of Nitrogenous wastes (ammonia) by diffusion thru the cell membrane

Reproduction Both sexual and Asexual reproduction occur Binary Fission- simplest asexual, occurs by mitosis producing two nuclei which separate when cytoplasm divides. Two identical cells Some organelles duplicate as well to ensure each new cell is complete Budding- mitosis produces new nucleus which is passed into cytoplasm much smaller than parent Multiple Fission- mitosis produces many new nuclei which are passed on to multiple daughter cells Sexual reproduction- sexually mature individual is haploid, gametes produced by mitosis, meiosis follows union of gametes

Super Groups Excavata-Have feeding groove, flagellum or had one, feed by flagella generated current Giardia- Anaerobic metabolism, causes waterborn disease in U.S Trichomonas- flagellated, causes sexually transmitted disease Euglena- flagella, posses chlorophyll, photosynthetic, pigment shield allows them to orient towards the light Trypanosoma- cause African sleeping sickness from bite of Tsetse fly, attack central nervous system, Death if not treated Amebozoa- when feeding and moving they form temporary extensions called pseudopodia, some lack a test or cell wall others have a test of calcium carbonate or chitin Tubulinea- live anywhere they can remain moist, free living forms form tests of cemented minerals, many are parasites of invertabrates, fish, and mammals Acanthamoebida- aerobic inhabitants of soil and water, two types are parasites of humans, one attacks brain the other infects the eye Entamoebida- use pseudopodia to capture food, lack mitochondria, cause dysentery in humans by ulceration and inflammation in lower intestinal tract, diarrhea contains blood and mucus

Giardia

Trichomonas

Euglena

Trypanosoma

Tubulinea

Acanthamoebida

Entamoebida

Super Groups Rhizaria- related to amoeboid some have fine pseudopodia used for feeding Foraminiferia- primarily marine, form test of calcium carbonate, resemble spiral shells from beach, abundant in fossil record, formed chalk cliffs of Dover, planktonic Heliozoans- some naked some have test with holes for axopodia, planktonic Radiolaria- Planktonic, marine and fresh, radial symmetry test of silica, very porous for axopodia Chromalveolata- diverse group, autotrophic mixotrophic or heterotrophic, all have plastids Dinoflagellates- one flagellum that wraps around a central groove, spins on it axis, second flagellum propels it, contain chlorophyll and xanthophyll (reddish), can become so numerous they cause red tide and produce toxins that kill fish, Red sea was probably named after this Plasmodium- tropical, causes malaria, 100 million people contract it yearly, is a bigger problem with global warming, spread by mosquito Cryptosporidium- causes chronic diarrhea, only known protozoan to resist chlorination Toxoplasma- found in cats and birds, spread in cat feces, causes stillbirths and spontaneous abortions in humans, fetuses that survive show mental retardation or epilepsy, keep cats away from sand boxes, no raw meat. Paramecium-cilia covered membrane, ciliated oral groove leads to food vacuole, sexual reproduction with micronuclei, many live in the gut of hoofed mammals and contribute to digestion